text:
What is this airport video?
I was in a car dealership waiting room and saw this video of an airport that was slowly scrolling down the screen (like River Raid).

The video is in motion - the cars on the street are moving and the 2 planes on the left were taxiing. The scrolling is very smooth - as if it's a satellite or maybe blimp.
Is this real video or just CGI? What airport is it?
How did they get the video while it was obviously in use? Wouldn't the airspace above the airport be restricted?

Specifically, the video is one of the Apple TV's screensaver images, taken at LAX (this one in particular [WARNING: high-def video link, ~267MB] [alternate YouTube version, thanks to Mark]).
It's not CGI. Apple used a variety of drones and helicopters to shoot the footage.
While the airspace around the airport is generally controlled (not restricted), there are a number of VFR flight routes that cross the airport. These can be seen on the Los Angeles Terminal Area Chart. In the case of this specific video, permission was presumably coordinated with ATC. As the video was taken down the middle of the airport, between the sets of runways, it's likely that taking it didn't interfere with air traffic; traffic arriving/departing LAX won't be flying there.

This tweet (with photos) just crossed my feed. @ethanklapper: Today was special. Chartered a helicopter and flew above LAX at 2,500 feet. Took 500 pictures in an hour. Can’t wait to share more!
I imagine a similar process was used for this video.

Note: The high-def video link is a direct link to a .mov file that's ~267MB.

You can add Youtube link https://youtu.be/h_0jv-g1Nl8?t=4m23s with this particular moment, so there is no need to download 267MB movie ;)

Thanks @BruceWayne and Mark. I was on a fast connection so I didn't really notice the exact size, beyond figuring it was probably large enough to require some kind of warning.

Thanks. I would have never guessed that it was some kind of screen saver or was made by Apple. Almost makes me want to get Apple TV.

Plane Spotting is done regularly over LAX. In fact there are a number of helicopter tour companies that will fly you over LAX often with open door. Here is one tour company that has a map of the areas they can fly over.

Also in the Sept. edition of Airliner World they talk about the process in more details.

This is the Tom Bradley International Terminal (TBIT) at LAX.
Though I'm not sure how they filmed it. If it's moving in real time I don't think it's satellite. Drone seems like it may make the most sense, but it seems like it would be a huge pain to get permission to fly a drone right there, even though planes are not (hopefully) flying that low over the terminals. Maybe another poster can chime in.

You can tell by the distorted airplane tails that the video was shot at a fairly low altitude with a wide angle lens.  The further left or right from the center of the video, you can see more of the vertical surfaces.


text:
How does air conditioning work on a commercial airliner?
I know a lot about airplanes, but I've always wondered the vents deal with air pressure in the sky

The answers to this question explain that in quite a bit of detail.

Came across this diagram that sums it up pretty nicely:

You get 'bleed' air from the engine compressor stage. On 'bleedless' aircraft, such as the B787, this is done by electric compressors instead.
Air temperature and pressure is adjusted as necessary in the conditioning packs since it heated up a lot when it was compressed.
Air is then distributed to the different 'zones'. A bit of the cabin air is recirculated.
Some areas, such as the cockpit, generally receive air directly from the packs without recirculating at a slightly higher pressure, to blow possible smoke away from the interior and to prevent smoke being recirculated into the cockpit. For the same reason, you try create a flow out through the baggage hold.

Here is a more complicated diagram from avsoft's website for a CRJ200:

source: Stack Exchange

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text:
If engine rotation was in reverse would it result in some kind of thrust reverser?
I mean if you rotated the propeller the other way would it result in reverse thrust.I wonder this because the propeller has to rotate in a certain direction to produce thrust, but would putting it in reverse cause a force to help stop the airplane?
And does this system exist with planes that have propellers?

Hi Ethan, you should include links to sources in your posts, and this image is not really free to use.

Absolutely, but as others have said it would be a very inefficient brake.
It's much more effective to simply rotate (or "pitch") the blades into a beta (zero-thrust -or- "flat pitch") or into a negative-pitch (reverse-thrust) condition.  This is a common feature on virtually every turboprop engine and many large, powerful radial engines.  It seems to be an emerging feature for small piston aircraft, although it is still rare to see a small piston airplane with a reversing propeller.  They do exist though but they are mostly sea planes.
Looking at the picture that you provided, the silver dome thing from where the propeller blades sprout is the hub of the propeller.  The bases of blades "plug" into this hub and can rotate through a certain range dictated by a device called a "governor."  The pilot can adjust a propeller control (usually part of throttle or power lever) that tells the governor to rotate the blades forwards or backwards.  During take-off, the pilot pushes the power forward which tells the engine to speed up and tells the propellers to push A LOT of air backwards for thrust.  When the pilot pulls this engine lever all the way back (on the runway during landing), he's telling the propeller blades to rotate in their sockets and push air forward instead of backwards.  Passengers hear this happen on landing as a loud roar for a few seconds as the plane slows down on the runway.  It feels like the pilot slams on the brakes but it's mostly the propeller blades reversing in their hub sockets and pushing air forward to slow the plane down.  You can also hear the pilots adjusting the propeller blade pitch to control taxi speed as you taxi around the airport but this isn't as noticeable as the landing noise.
It's important to realize that the engine will ALWAYS spin the propeller in the same direction.  It does not stop and then spin another direction.  The only thing that changes is the "pitch" of the blades in their hub sockets.
Hope this helps.

The propellers are like airfoils. Just as the airfoils do not produce useful lift if flown backwards, the propellers don't produce thrust if spun in opposite direction.

Source: www.quora.com
That being said, it is possible to obtain reverse thrust from propellers by setting a negative pitch, similar to the airfoil being flown upside down.

Source: 12charlie.com

"Just as the airfoils do not produce lift if flown backwards" -- I don't think you can say this definitively.

@Porcupine911 Depending on the shape, some airfoils do produce lift in reverse flow, just that it is not efficient and useful. Poor choice of words. Thanks for pointing it out.

The propeller spinning in reverse would be like flying a wing backwards... it wouldn't be efficient, and it probably wouldn't accomplish much of anything.  (Ceiling fans CAN be spun backwards to generate a breeze in the opposite direction, but they aren't exactly sophisticated airfoils!)
Spinning an engine backwards doesn't happen because you'd have to stop and then reverse direction of a lot of mass --- way too much momentum to reverse the direction of rotation unless you took a long time to do so.
When props go into reverse thrust, the engine & propeller continue to spin in the same direction, but the angle of the blades is changed so that the thrust vector is now in the opposite direction.  That process CAN happen pretty quickly, so you have reasonably immediate reverse thrust available.

I think a bigger issue with ceiling fans is that regardless of which direction they're turning, they're pushing air in the direction it's moving.  By contrast, unless one is trying to taxi in reverse, reversing thrust would imply that a propeller was trying to push air in the direction opposite the direction it was moving, thus reducing the amount of new air flowing over the propeller.

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text:
If you removed the compressors in an airlines engine would it have more thrust?
I was reading something about jet engines and it stated that the exhaust comes out of the exhaust nozzle at about 1,300mph, and it also said that the compressors help reduce the speed of the air flowing into the core, so is this true? Link for the website it is on

Related

"If you removed the compressors in an airlines engine would it have more thrust?": No, it wouldn't work as well. The other part of the sentence explains that the compressor increases the pressure (hence its name). Without this pressure increase, the engine wouldn't work (at least at subsonic speed).

@mins So it would be slower.

If you remove all compressor stages, as your question implies, then the engine should not start or run at all. The compression is needed unless the speed of the engine is large (supersonic) and enough air enters the engine without being assisted. This type of engine is named ramjet. In that case the turbine is not needed either, since it exists to turn the compressor.

@Ethan Yes, much slower. Around 0 mph. It might make a nice flame if you tried to start it, though.

It would work as well as a diesel piston engine without compression, ie not at all.

In case of jet engines, compressor increases the pressure of the incoming air, which carries out two functions:

The pressurised air aids in the combustion with increased effeciency. If the air is not compressed, especially at high altitudes, the combustion process will grind to a stop.
If there is no compressor, and by by some miracle combustion happens in combustion chamber, the low pressure in front means that the flame will exit in all the directions. This will stop the turbine.
If the compressor is not there, the engine cooling will not be there and combustion chamber and possibly the turbine blades will melt.
If the compressor doesn't reduce the air velocity, combustion process will become extremely difficult, the problem faced in scramjet.

In short, if there is no compressor, there will not be an engine as we know it.
The closest engine comes to having no compressor is during a compressor stall, when all the above things happen- the engine flames out and loses thrust while flames exit all over the engine.

In some cases, the engine is damaged beyond economical repair.
There is a type of engine without compressor- the Ramjet engine. However, even here, the incoming air is compressed by the inlet. This engine has no turbine.

"Ramjet operation" by Vector image made by Cryonic07. Sourcepng-drawing was made by Emoscopes and later slighlymodified by Wolfkeeper - Based on Image:Ramjet operation.pngThis vector image was created with Inkscape, and then manually edited.. Licensed under CC BY-SA 3.0 via Commons.
However, the ramjet engine cannot start by itself and can operate only at supersonic speeds.

If you remove the compressor stages entirely, you no longer have an engine.  You will have a combustion flamefront that expands in both directions and will not provide enough flow to power the turbines.  Lack of cooling flow provided by normal airflow will result in the metals in the engine core melting and likely damage the engine beyond repair.
In short, removing the compressor yields an expensive paperweight that turns into scrap metal if you ever turn it on.


text:
Do turbo prop airliners generate thrust using the propeller and compressed air or just the propeller?
I looked at a picture of a q400 engine and it showed air being compressed so I was wondering if it has two systems to generate thrust.

Turboprop engines transfer almost all of the turbine's rotational energy to the propeller, though there is some waste in heat and exhaust gas as in all engines. The exhaust does not form any major amount of thrust unlike in other turbine engines ("jet engines", like a turbofan or turbojet). Turboprops are more efficient than other "jet engines" at lower altitudes due to the thickness of the air at lower altitudes whereas jets are more efficient at higher altitudes, though turboprop pilots will tell you they fly a jet, being that a turboprop is still a turbine engine, aka a jet. :-)

The PT6A provides approximately 10% extra thrust from exhaust gas
http://www.turbokart.com/about_pt6.htm

Where does the linked article say so? I can't find it. Also many aircraft employing PT6A have the exhausts mounted so that they only loosely direct the exhaust gas to the rear (PT6A is a reverse flow engine; the gasses exit the engine itself forward) and nothing like a nozzle that could generate thrust.


text:
What are these antenna-like protrusions for on an airliner?
This is a JetBlue A320:

I've always wondered what these are for, but could never find the answer. I'm guessing a few of them are for receiving information from satellites.

Labeled them in numbers so you can describe what each one of them is for. Yeah I finally figured out how to get images from google drawings onto my question :)

They are the various communication and navigation antennas of the aircraft. This figure shows the location of antennas in A320, the type of aircraft in picture.

Source: pprune.org
Some antenna (the ones with *) are optional and the installation varies with customer. The communication antenna location in A320 can be seen in this image.

Image from airbus training course from airbus.altervista.org
And the navigation antenna location in this one:

Image from airbus training course from airbus.altervista.org
The dome (2 in the picture) is the radome for the wi-fi system introduced by Jetblue, dubbed Fly-Fi.

Source: nycaviation.com
So,

1,3,4 - VHF
2 - Wifi
6 - ELT

Actually 2 is probably the DirectTV antenna... maybe coupled with Wi-Fi

@slookabill Maybe. It has WiFi allright. See the vox article on this

Why call it Fly-Wi when they could have easily called it Wi-Fly...

@immibis Apparently it is called Fly-Fi. Sorry for the mistake, though I'm in no position to answer why they came up with that name :)

Just a guess, but Wi-Fly might already be trademarked by a competitor.

@DanHulme - wi-fly is full of connotations negative for the bottom line. Rejected by marketing.

"Wi-fly? Because now there's Fly-Fi, your Fly-Wi solution for WiFi while you fly."

@ToddWilcox, don't give up your day job for a marketing career ;)

looooooooooooooooooooooool

I find it interesting that they list TCAS and GPS as optional...

@reirab: Along with the HF, ELT, and SATCOM antennae.

@sampablokuper Please ask that as a new question rather than asking in the comments.

@Sean The ELT being optional is for MH.

@reirab: MH?  Malaysia Airlines?


text:
Seeking the memoir of a WWII Luftwaffe pilot
Around 40 years ago, or perhaps a little earlier (say around 1980), I read the memoir (or perhaps the biography) of a fighter or perhaps light-bomber pilot who flew for the Luftwaffe on the Russian Front. I have no idea when it was published, other than guessing that it was probably after about 1950.
The only detail I can now remember is that he was captured (presumably having been shot down), and charged with having caused civilian Russian deaths because of all the spent cartridges falling from his aircraft during many combat sorties.
I think that he was incarcerated following trial, and then possibly repatriated within some kind of prisoner-exchange arrangement.
For years I felt sure that this book was Hans-Ulrich Rudel's Stuka Pilot, which I also read around that time. I recently got another copy of that, however, and found that after all this time I was clearly mixing-up two different books.
Can anyone suggest the book that I have forgotten, or at least the identity of the pilot?
I wish I could offer more detail, but this is all I have, and research from the ground up is getting me nowhere. I think I need somoeone's actual knowledge!

I think you are referring to Erich Hartmann.

That was amazingly fast! . Please see my comment on @Niels Nielsen's suggestion, for the reason why this came to mind after all this time, and for an idea of the angles I am considering. I am interested (always have been) in the conduct of WWII German officers who may have been acting in good faith without being out-and-out Nazis. With the Luftwaffe we have Galland, who seemingly tried to make peace, against Rudel, who (I think) went on to set up post-war South American refuges for genuine Nazis. There is also the problem that some genuine supporters' reputations seem to have been whitewashed.

@CaptainCranium I live in Germany and a few weeks ago I stumbled across a book about Hartmann on the local ebay. It had an aircraft on the cover so it naturally attracted my attention. I had never heard of him before and did a bit of research. When I saw your question it sounded very much like what I gathered about him. Glad I could help!

Or you could be referring to Adolf Galland.

That is a very good call -- thank you!
As it happens I think that @DeltaLima has identified the source (Hartmann) of the specific book I was looking for, from 40+ years' memory failure... but Galland would add very usefully to what I have in mind.
The project that I am considering is a delicate one.
It was motivated by my feeling obscurely troubled about a British documentary radio series, 'History's Secret Heroes' (https://www.bbc.co.uk/programmes/m001mcbk), unilaterally praising groups who did brave things (no longer very 'secret', anyway) opposing Hitler and his evil friends.

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text:
why standard wrenches are sized like 1",15/16",7/8",1/4" etc?
There is a belief that wrench size is the across the flat distance of a bolt head/nut. any reason other than this for designing wrenches in these standard sizes?

Welcome to Aviation.SE! For aircraft designed and built in the USA, yes, this is the standard for hardware and tooling. The reasons are not particular to aviation, but have to do with the standards of measurement and the history of industrial development in the US.

Seems to be related to Renard's series, further detailled on Wikipedia.

Because a wrench wouldn't work if it didn't match the bolt head.  Bolts and (wrenches to fit them) come in standard sizes because... Well, can you imagine the confusion if they were all different?  It's bad enough keeping Imperial and metric straight.

Spanners and all hand tools are based on the bolt head size, eg, 3/8" across the top of the flats of the bolt head, note, this is not the bolt shank size, the threaded part. Because most widespread use of tools began in the US, the Imperial system of tool sizing came from there. In the last 30 or so years, the metric system has become widespread, but as aviation is largely based on the US system, the imperial system of measurement largely remains. There were some other forms of tool measurements uses, the UK BAE and Whitworth sizes but fortunately, these never became widespread, otherwise, your toolbox became a nightmare of tool sizes. Yes, been there, had that.

"most widespread use of tools began in the US" [citation needed]

@DavidRicherby  Unga-Bunga?

Because most widespread use of tools began in the UK during the industrial revolution when the imperial measures of tools were invented - there, fixed it for you.


text:
Can old passenger airplanes be refitted with latest engines to extend their life and efficiency?
I was wondering if this might make sense as commercial aircraft design has not changed significantly (from the outside) in the last 50 years?

What makes you think this hasn't already happened?

Not changed much in 50 years? Aerodynamic efficiencies have improved massively, as has the materials used to build the fuselages and wings. These alone have produced massive fuel efficiency gains!

This question could use some clarification, as new models are obviously being built that combine older airframe designs with new engines (737, 747, A320 all spring to mind immediately). I assume you're asking if an airplane built in, say, the 1980s could be updated with 21st century engines?

You are absolutely right - refitting new engines to older airplanes makes a lot of economical sense. After all, two thirds of fuel economy gains in the last 50 years were due to better engines.
However, some conditions conspire to make this harder than it might look:

The better efficiency was gained by increasing the bypass ratio of engines, which means that the new ones had more diameter for the same thrust. This makes them hard to fit to airframes designed for the smaller engines, and adding a longer landing gear would be too expensive - then it is indeed better to buy a new airframe.
Designs with tail-mounted engines would have center-of-gravity problems with newer, heavier engines. Tail-mounting engines was very popular after the Sud Aviation Caravelle pioneered this, but rules out those designs (BAC One-Eleven, Vickers VC-10, Boeing 727, Illyushin 62, DC-9, Tupolev 134 and 154) for refitting with more modern engines.

Add to this that airframes have a limited life time, and fitting new engines makes sense for only a limited number of aircraft.

Regarding No. 1, the B737-300 transition to the CFM56 from the old JT8D  engines used on the B737-200 overcame this drawback, but on a new model designation.

@JonathanWalters: Yes, and that is why I linked to the article on the odd shape of the engine inlets. Developing those was a major effort, even for Boeing, so the big engine could be fitted into the restricted space between wing and ground. Note, however, that Boeing has since also added a newly-developed wing to capture the benefit of supercritical airfoils.

Um, the DC-9 series is too capable of carrying modern high-bypass turbofans without having CG problems, as demonstrated by the DC-9-93/95 series.

@Sean: The V-2500 has 350 kg more dry mass, and those 700 kg at the tail need to be compensated somehow. That the engineers solved the cg problems does not mean that there were none.

@PeterKämpf: No, but it does mean that they were solvable - which contradicts your assertion that having tail-mounted engines "rules out those designs... for refitting with more modern engines.".

@Sean: Seems you found the one exception that proves the rule.

Yes, this can and does happen.
Two examples that I think are excellent illustrations of the concept are turbine conversions of the Beech 18 and the Douglas DC-3. In these cases the old radial piston engines were replaced with turbo-prop engines. Other examples also exist, including less drastic modifications.
An example of a Beech 18 modification is the Volpar Turbo Beech conversion which used Garrett TPE-331 engines. Information on that conversion here, and an example of the operational use of such modified aircraft here.
An example of a DC-3 conversion is the Basler BT-67, which uses PT6A-67 series engines. Information on that conversion here and here.

It's certainly possible for aircraft to be retrofitted with newer engines. One example is the DC-8 Series 70, which had the older JT3D engines replaced with more efficient CFM56 engines. However, there are many reasons for this process not being more common.
There are many costs associated with changing engines. The engine may need a new nacelle design to fit the specific aircraft. This will probably require a new or at least revised strut design to mount to the wing. The wing may also need to be reinforced, as newer engines tend to be heavier. All of the systems attached to the engine, including electrical, hydraulics, and bleed air may also need changes. Avionics will also need to be updated to work with the new engine type.
Certification also should not be overlooked. Assuming the aircraft can use an existing engine that is already certified, the aircraft will still need to be certified to fly with that engine. This means a lot of paperwork with the regulators, and probably additional testing. However, engines tend to be designed for a specific aircraft type. For example, the CFM LEAP engine will power the A320, 737, and C919. All of these aircraft are similar in size and compete for the same market, yet CFM is doing testing and certification of a different version of the LEAP-1 for each of these aircraft. Each manufacturer chose to design their aircraft for a different engine version, which makes it seem unlikely that a new engine would just happen match the needs of an existing aircraft without extensive modification of the engine.
Aircraft fuselages are designed with a limited life span. As they age, maintenance costs increase as more work is required to repair damage from fatigue and regular wear and tear. Even with new engines, the airframe would still have a limited life span.
As other answers have pointed out, a new airplane design will be more efficient than just putting new engines on an old aircraft. Owners of the older aircraft would have to see a benefit in paying to upgrade their old aircraft, and having those aircraft out of service for an extended period, versus just buying a new plane that will be more efficient and will have many more flight hours left ahead of it. And some company will need to find enough of these customers to justify the large upfront costs listed above in making such an upgrade possible.

The CFM re-engines were the first thing I thought of. Basically the same engine upgrade was applied to KC-135s (the original Boeing 717) to produce the KC-135R & KC-135T.

While the design of aircraft may not look different to previous generations of aircraft, the technology behind them is vastly different, from lightweight carbon fibres, to far more aerodynamic wings. New design aircraft provide vastly better operating economics than aircraft based off an old design but with newer engines.
Take for example the A350, which Airbus claim delivers a 25% fuel reduction per seat when compared to existing aluminium long-haul aircraft. The A330neo on the other hand, which is a re-engined version of the A330 (but also containing revised wingtips and some other minor aerodynamic enhancements), is only expected to deliver a 14% fuel burn advantage per seat over the current A330.
And this is with a newly built A330neo rather than taking an old A330 and putting new engines on an existing frame.
There are many reasons why putting new engines on older airframes are not a good idea. First off, simply swapping out the engines is not feasible - the chances are the new engines will have different mounting points, and different fuel flow requirements, requiring a complete redesign of the fuel flow system. You would also need to revise the avionics, to take into account revised engine operating parameters. Operating procedures for pilots would also be different between models, leading to either the need for separate pools of pilots per engine type, or if pilots are crossing between models, an increased risk of pilot error leading to an accident.
But the biggest reason why this is not done, is that aircraft fuselages have a limited lifespan. With every flight, you are pressurising the aircraft, then de-pressurising it for landing. This causes metal fatigue to the frame. This alone is the single biggest cause of aircraft being retired. It is required that aircraft undergo a "D-Check" roughly every 6 years. This involves stripping the entire aircraft, and removing all paint from the outside, so the state of the fuselage can be checked for signs of metal fatigue. This is a hugely expensive and time consuming process, and as a result most aircraft only every go through a few of these before they are retired.
So re-fitting an aircraft with newer engines would not be feasible as the air frame would have exceeded its lifespan anyway and would need replacing, so far better to just buy a new build aircraft.

While you make some valid points, there are several examples of aircraft being retro-fitted with updated engines. You suggest that it would never be done, rather than saying that it can be done but isn't often.

The fact is that modifications are feasible, economical, and are done, despite the drawbacks you note. However, some of the notable examples of this type of modification include passenger aircraft which are not pressurized, negating that otherwise valid drawback.

@JonStory yes, you're right. I was referring to modern aircraft in my answer. It may have happened in the past, but nowadays it's just not economically (and possibly technically) feasible.


text:
How are the accessories of fighter jet engines oriented (Turbojet or Low-Bypass-Turbofan)?
How and why are the accessories of modern fighter jet engines oriented with respect to the airplane? Do the subsystems show up (see left image part) or down (see right image part)?

Wow classic homework question!!

My first thought was "in the least convenient position for maintenance".  I hope I'm wrong.

If you're downvoting because this looks like a homework question, please review this meta discussion first. We have no explicit policy on them and as some answers in meta say, even if a question is indeed for a test, good answers can still be interesting and helpful for other people.

Engine Accessories On the Bottom
The engine looks like the General Electric GE F414, which is used (amongst others) in the Boeing F/A-18E/F Super Hornet and the Saab Gripen NG. In this case, the engine is mounted with the accessories below, i.e. in 6'O clock position. See this image:

An Aviation Machinist’s Mate (AD) performs maintenance on an F/A-18F Super Hornet. ADs are aircraft engine mechanics. They inspect, adjust, test, repair and overhaul aircraft engines and propellers. Image from americasnavy.tumblr.com
It is not correct that the engine accessories 'protrude below' the aircraft. The fusealge design is such that there are no protrusions, as can be seen in this image.

"US Navy 040708-N-9060G-009 Aviation Machinist's Mate 3rd Class Evonda Patterson, of Chicago, Ill., performs scheduled maintenance on the engine of an F-A-18E Super Hornet" by U.S. Navy photo by Photographer's Mate 3rd Class Michael Geary
Apparently, the reason for mounting the accessories down is for ease of maintenance as they can be accessed easily this way.
Other engines with the accessories on the bottom are e.g. the Pratt & Whitney F119 for the Lockheed Martin F-22 Raptor, the Eurojet EJ200 for the Eurofighter Typhoon and the SNECMA M88 for the Dassault Rafale.
Engine Accessories On Top
However, this varies from aircraft to aircraft, as evidenced by this Sukhoi Su-30MK with Saturn AL-31F(P) engines with the accessories on top.

Image from researchingaliensandufos.com


text:
why does the concorde's nose go up and down
I have wondered this when looking at pictures of the concorde and sometimes it was down and other times it was up and why cant the commercial airplanes have this system.

When the Concorde is in supersonic flight, the shape of the fuselage has to be very aerodynamic.  On landing, the attitude of the plane is very nose high, so the nose comes down to allow the pilots to see the runway.

For any aircraft, the slower you fly, the more the nose is up. For a delta-wing aircraft like Concorde it's even more so, and supersonic flight requires a very slender fuselage. This means during landing and takeoff the nose will block the view forward, and lowering it allows the pilots to see in front.


text:
What is downwash on a wing and how does it form?
This is a subject I have been very confused with lately about thrust coming from downwash on a propeller and helicopter, but to understand how the downwash increases thrust is to know how it forms and works on a regular aircraft wing. A picture of downwash on a wing would be helpful. And also how does downwash make thrust on a propeller and helicopter wing?

@RedGrittyBrick Not a duplicate none of the answers in that question explained downwash.

Did you try to search "downwash" on this site?

It is the words you are confused about. As others have said before in your many questions on this topic, a helicopter rotor blade, a propellor blade and a wing are all the same. They generate a force from air moving over them. The only difference is the direction in which the force they generate normally points. The downwash on a propellor normally goes backwards, not down. The downwash from wings and rotors go down. They do not increase thrust, they are the thrust, according to Newtons 2nd, which causes the propellor to pull, and the rotor blade or wing to lift.

It is only called downwash on a wing or a rotor.  On a propellor, it is called prop wash (or other terms) but the only reason to use different words is because the prop wash does not go down.  Therefore calling it downwash would be confusing.  Your confusion stems from wherever you read or assumed that the airflow moving back off a propellor is called downwash.  Just understand that propellors, rotors and wings are all just aerofoils and work in exacactly the same way.  Speed of relative airflow and angle of attack to produce a force.

Newtons 2nd law tells you why downwash produces thrust.  If you accelerate air downwards (which is what downwash is) there must be an equal and oppopsite force upwards.  This is lift (wing or rotor) or thrust (propellor).

Having in mind a typical flow around an airfoil, the flow over the wing flows much faster than the one under the wing. This faster particles arrive first to the trailing edge and are "projected" against the rest of the flow, creating that additional thrust.
Moreover, the difference between the free stream and the flow after the trailing edge is the downwash angle. I hope it helped.


text:
What is this number in the bypass ratio?
Here is an example of a bypass ratio 9:6:1. 9kg goes around the core and 6kg goes into the core, but what is the 1 for.

By the way this is the bypass ratio for the General Electric GEnx-1B engines on the 787 Dreamliner.

The bypass ratio of a turbofan engine is the ratio of the mass flow rate of the air that bypasses the engine core (i.e. it doesn't undergo combustion),$\dot{m_{f}}$ to the mass flow rate of the air that passes through the core $\dot{m_{c}}$ and undergoes combustion.
The bypass ratio is usually given as the mass flow of fan by the mass flow of core i.e. $\frac{\dot{m{f}}}{\dot{m_{c}}}:1$. In some cases, it is given as the ratio of cold air to hot air, $\frac{\dot{m{c}}}{\dot{m_{h}}}:1$.

So, a bypass ratio of 9.6:1 means that 9.6 kg of air passes through the bypass fan for every 1 kg of air passing through the core.

It is 9.6:1  not 9:6:1.
9.6 parts air are bypassed for each part that goes through the core.

That makes more sense


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How long is this part of the Boeing 737 and cockpit?
 I can never find information for the length of each of these areas. For the cockpit length is the nose to the bathroom and the back of the airplane is the coffee symbol to the tail of the aircraft.

I typed "boeing 737 dimensions" into google and quickly found https://www.flickr.com/photos/wbaiv/sets/72157622773807476/, among other things.

@Airsick My goal is to design an aircraft that will change the future of flight. Almost all of my questions have had something related to the design. I want to know the dimensions to know how big to make the tail and cockpit of the aircraft.

@GregHewgill That's weird I have typed in boeing 737 dimensions and never found this information on google.

@Airsick I know but I want to get the basic idea of the lengths for the tail and the cockpit.

You already have a scale drawing. Wikipedia tells you the total length of the plane. Your profile says you're 14 years old. By the time I was that age, my school maths syllabus had definitely included how to use ratios, which are enough to calculate any dimension from a scale drawing where you know one of the dimensions. If you don't know even that basic mathematics then I'm sorry but you're unlikely to be able to design any working aircraft, let alone one that will "change the future of flight".

@DavidRicherby I know, but I want to come up with the concept at my age. Then when I get older and learn more mathematics I could then fully design the aircraft. You would be surprised about my design and how complicated and complex it is( and maybe it will change the future of flight I have some ideas that are new)

I would venture to say that the specified portion of the aircraft is exactly as large as it needs to be to contain the items that need to be there. Any smaller and the cockpit related items (seats, controls, monitors, electronics, etc) wouldn't fit. Any larger and the designers are wasting space that could be used for fare-paying pax. I would suggest that your revolutionary design use this methodology, as well.


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What type of flow is preferable for jet engines?
I would like to know how laminar/turbulent flow affects engine performance. Any additional thoughts on the topic, even if not strictly related to the main question, are welcomed.

Laminar. Turbulence is bad if you want the engine to keep spinning.

@Lnafziger Could you explain how it exactly affects the engine?

Thanks. I wanted a deeper answer because I was wondering if turbulent flow could help in the combustion process, not only in compression.

Yes, induced swirl or turbulent flow can be helpful in the combustion section for a variety of reasons. If focusing on the combustion section is your intent in asking the question, you might find it helpful to specify that in your question.

Unfortunately, I can't in a technical manner for this particular issue, but there are other people here that have more experience with his that will be able to help you! (that's also why I only posted a comment rather than an actual answer.)

The noise within the engine will make all flow turbulent. There is not much liberty for the engine designer to choose the type of boundary layer.
Generally, a laminar boundary layer is preferable as long as the flow is accelerated, because viscous drag will be lower, and a turbulent one is better when it is decelerated, so separation can be delayed.
Outside of boundary layer phenomena, turbulence is helpful for keeping the combustion process going in the combustor and especially in the afterburner. Ahead of the combustor all engines have a diffusor to slow down the compressed air, so it has time to mix with the fuel and burn as much of it as possible. Note that the diffusor only slows down the axial movement of the air, so radial velocities will not be affected and be relatively larger relative to the axial flow at the entry of the combustion chamber. This makes the flow more turbulent, which is helpful for better fuel-air mixing.
In the afterburner, flame holders are needed to produce pockets of slow-moving, hot gas which can ignite the fuel-air mixture. Again, they cause more turbulence.

Flame holder (10) with annular selectors (9) of an afterburner (picture source)
At the nozzle, turbulent mixing of the hot core flow and the bypass flow reduces noise. Engine nozzles use a variety of means to speed up the mixing process.


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Does skin friction drag decrease with velocity?
The wings of subsonic planes have usually a very low surface area and aspect ratio as big as possible. However, in supersonic aircraft, wings with more wetted area (e.g delta wings) are used. Is this because skin friction decreases with speed or because in supersonic flight this type of drag is no longer the main concern?

Your question is about friction drag while the text is mainly about aspect ratio. You seem to explain the choice of aspect ratio to be based on friction drag. This is not correct.
Here and here are some good answers to explain the choice of aspect ratio. You will see that it has mostly to do with structural strength and wing volume to pack enough fuel. For supersonic aircraft the delta wing provides a highly swept leading edge, a stiff, light wing and good low-speed characteristics even with the thin airfoils which are helpful in supersonic flight.
Generally, aspect ratio becomes less important the faster the aircraft flies, because it has more air flowing past per unit of time  for creating lift. At supersonic speed some of the drag is proportional to the local inclination of the surface, so the designers try to make the aircraft as sleek as possible. To put it bluntly, a subsonic aircraft likes to be as wide as possible to reduce induced drag, while a supersonic aircraft likes being longer to reduce wave drag.
Friction drag will go up with the square of velocity if all other parameters are constant. Since a higher velocity increases the Reynolds number (the ratio of inertial to viscous forces), in the real world the increase is slightly less than with the square of velocity. Since lift also goes up with velocity squared, the airplane can fly at higher altitude where the density is lower, which reduces both lift and drag.
Now you need to consider the change in temperature over altitude: Air gets cooler when it expands, and cooler air causes higher viscous forces. By flying higher, the Reynolds number goes down again and the viscous drag goes up. In total, flying faster and higher will result in a slight increase of the absolute friction drag at the same lift.
If you plot the drag coefficient over flow path length you will find that lengthening the flow path will generally increase drag less than proportionally. Only when the boundary layer is laminar and lengthening the flow path adds a turbulent transition will you find that friction drag briefly goes up more than proportionally. Sometimes it is helpful to force that transition, but mostly it comes sooner than the engineers like.
Please follow the links and read the linked answers, only then is this answer complete.

Thank you very much for the answer, all the links provided are very informative. I understant that A.R is not as important in supersonic flight as it is in subsonic, but it is still not clear to me why delta wings are chosen. Is it because it helps reduce wake drag in some way or because it has something to do with the area rule?

@user15037: Maybe I should had added this link as well. They provide sweep, stiffness and good low-speed characteristics even with thin airfoils.

I see, thanks again.

They need the wings to stay within the shock cone. There's a cone shaped, supersonic shock wave riding off of the nose tip, and the point of the delta wing design is to keep the wings fully within this cone so that they see local sub-sonic airspeed only.

@Koyovis: Only in supersonic flight, and yes, the idea is to keep the flow component perpendicular to the leading edge subsonic. The airspeed over the wing is still supersonic, however.


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How to convert body frame-relative aerodynamic coefficients to wind frame-relative aerodynamic coefficients
I have a rocket flight simulator that takes in aerodynamic coefficients defined relative to the vehicle body frame axes (Cx, Cy, Cz). These are in a lookup table based on mach.
I have some aerodynamic coefficients that are given relative to the wind frame (Cd, Cl), also with a lookup based on mach, and I would like to input these into the simulator.
Is there a good way to convert the coefficients to the body frame so that they can be compatible with my simulator?
I know that I could modify the simulator code to make the transformation at runtime, but I was wondering if there is a way to do it where I could convert the coefficient lookup table itself.

Does this answer your question?

All it takes is a 'little' trig.  If you want more information than you need, check out AEDC-TR-63-224.  To skip to the answer, look at eq 42:

I considered this a case of LMGTFY and only pasted in the link to the technical paper that derives the equations, lays out the nomenclature, and explains everything.  Ralph copy/pasted the final answer (the image with some letters) feeling that made the answer more complete.


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How altitude changes with changed QNH?
How the AGL altitude changes with changed QNH? I'd like only to confirm or correct my intuition..
Airplane is maintaining certain FL with some QNH, its instruments are showing some AMSL. Now the airplane enters area with lower air pressure, but keeping the same set QNH. How the real AGL altitude changes?
My intuition is that altimeter is effectively showing certain pressure. If the atmospheric pressure drops (e.g. from 1013 to 990), to show the same measured pressure (altitude) the airplane has to descend.  Then the airplane is having lower real AMSL than displayed on instruments.
Is my intuition correct?

Yes. There's an old saying: when flying from high to low, look out below! https://sabushpilot.com/high-to-low-look-out-below/ has nice properly descriptive image.

Airplane is maintaining certain FL with some QNH

Note that if you were at a FL (flight level), you wouldn't be using QNH, you'd be using QNE. You use QNH up to the transition altitude and clearances will be given to maintain a certain number of feet (or meters in some countries). Above the transition altitude, your clearance would be to maintain a certain FL and you would be using QNE, 1013.2 hPa.

Thanks for the answer, indeed I was using the term QNH incorrectly.


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How does de-icing work in an airliners engine
On snowy days the pilots well say to put on the de-icing on both engines how does this work?

I don't think the other question answers regarding the engine sufficiently. I  would like to answer and say that the crew will normally turn on anti ice whenever they are in visible moisture, the main thing that it does is apply heat to the engine EPR (exhaust pressure ratio) sensors at the front and rear of the engine to prevent ice build up. This allows the engine to continue making the correct thrust in accordance with its thrust lever position. An interesting link is here http://www.boeing-727.com/Data/systems/infoicerain.html

In simple terms, hot bleed air from the engine is ducted around the engine to prevent ice from forming. It is also directed through valves and ducting to the leading edges of the wings.


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Where does the oxygen come from in the deployable breathing masks?
I don't know what they are called. In case of emergency like smoke they deploy, but where do this oxygen come from.

As a side note, cabin masks are not typically deployed for smoke; they're not terribly useful (they just mix cabin air with some additional oxygen, so you'd still breathe in smoke) and they can be harmful (the generators get extremely hot, and they put more oxygen in the cabin which can fuel a fire). Flight crew masks are used for smoke, but they work differently and are able to supply 100% oxygen without any mixing with cabin air.

The oxygen is provided through Chemical Oxygen Generators. Oxygen masks are triggered either automatically given certain conditions or by the flight crew.

Oxygen generators are usually installed in above each seat row. If the cabin altitude reaches a predetermined height (14,000' is standard) or if the system is activated by the flight crew, overhead panels open and oxygen masks drop out. To put the mask on, it is necessary for the intending user to pull it down and this action releases the firing pin and activates the generator.
The oxidizer core of an oxygen generator usually consists mainly of Sodium Chlorate (NaClO3) mixed with <5% Barium Peroxide (BaO2) and <1% Potassium Perchlorate (KClO4). This core is activated by the application of heat generated usually generated by a mixture of lead styphnate and tetracene which itself is activated by a small explosive charge in a percussion cap are a mixture. This explosive charge is set off by the release of a spring-loaded initiation mechanism which is restrained until released by a pull on the lanyard which is visible when oxygen masks are released from overhead panels. Once activated, the chemical reaction and production of oxygen will continue until the generator has been exhausted which is typically in the range 12 to 20 minutes.

You might want to edit the second sentence?  I know what you mean but it does read as if the generators are triggered automatically which is not the case.

@Simon You are right, my bad!

It depends. Some aircraft have pressurized oxygen bottles.


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What is this B-52 carrying?
Source:(en.wikipedia.org)They look like fighter jets attached to both wings, but can't really tell what they are. What are these objects on the wings?

This is the picture from Wikimedia: https://en.wikipedia.org/wiki/File:B-52_with_two_D-21s.jpg. That picture appears on three wikipedia pages, each one captioned with a description of what is under the wings and a link to the Lockheed D-21 page. Please take the time to read the captions for photos you're looking at before turning to Stack Exchange for help.

@Ethan Greg is right. Please do take some time to go through the info.

They are Lockheed D-21 drones, an an American Mach 3+ reconnaissance drone. Here is a close photo.

"B-52 with D-21" by US Air Force - http://roadrunnersinternationale.com/d-21/D-21_historial.html. Licensed under Public Domain via Commons.
The D-21s were initially launched from Lockheed A-12, the predecessor of SR-71, but were switched over to B-52 after a fatal accident.


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Where are the bags generally stored on an airliner?
I don't mean carry on bags. What I mean is where are the locations of the non carry on bags on an airliner. Also does it depend on the airliner of where the bags are stored.Source:(gokaysarioz.com)

Related: How is the cargo hold volume for passenger aircraft designed?

In smaller aircraft, the baggage is put directly inside the cargo hold.

Source: jacksonville.com
In case of larger aircraft, the baggage is put inside the conformal cargo container or the unit load device, which is then placed inside the cargo hold.

Source: roger-wilco.net

Source: supath.net

On a modern large airliner (particularly for long haul), the bags are loaded into a ULD (Unit Load Device) which are the big silver boxes that you see on airport ramps. These ULDs are then loaded into the cargo hold of the aircraft, which is located directly below the passenger deck.
Here is a photo of the empty cargo hold of an A320 (source):

And this is what it looks like in cross-section after loading (this is an A300) (source):

I wouldn't strictly say "a modern airliner" always uses ULDs. Plenty of commercial transport aircraft fresh from the factory today are bulk loaded up to and including members of the 737 and A320 family, especially in the US. And brand new RJs will be bulk loaded too.

@ZachLipton: Good point, I'll clarify.

Don't think there are any belly cans for narrow body a/c. AKE's won't fit. They're bulk loaded.

Certain A320 aircraft have been ordered by carriers at build with a CLS - Cargo Loading System - Due the size of the hold space, there is a specific Unit Load Device that is manufactured for this aircraft - LD3-45 - the 45 signifying the height of the ULD that is compliant with the A320. A Standard LD3 as used on the Wide Body Types is 64 inches in height


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What is the typical speed an airliner has to reach before lifting in the air
I know generally it is about 170mph. But what is the actual speed in mph that an airliner has to reach before it takeoff's.

could you define "typical"? is an empty 737 typical? or is a fully loaded 380?

@Federico With passengers on it taking off from an airport.

@Ethan Still, what is a typical passenger airliner? A 737? An A380? An ATR-72? A CRJ-100? What airport? The air's much denser in the middle of winter at JFK than in the middle of summer at Denver, for example.

You may search for Vr or V rotate online. This is the name of the speed at which the rotation is initiated and the nose leaves the ground, the aircraft is airborne just after Vr. You'll see that Vr varies a lot, even for the same aircraft with the same engines.

You are asking a general question on airliners in general and state what the general answer is. What do you expect as an answer?

It depends on what type of an airliner you are talking about. Even then, take off or rotation speed in every flight is different. Pilots need to consider many variables like air density, aircraft gross weight, lift coefficient (aerodynamics of the plane), and aircraft configuration (flap or slat position, as applicable), according to Wikipedia. This is a few examples from the Aerospaceweb.org,

Boeing 737 at 100,000 lb, rotation speed is 150 mph / 130 KIAS.
Airbus A320 at 155,000 lb, rotation speed is 170 mph / 150 KIAS.
Boeing 747 at 800,000 lb, rotation speed is 180 mph / 155 KIAS.

Each plane has a set of calculations which pilots use to determine a specific speed (V1, VR - rotation, and V2) for each flight. Modern airliners come equipped with their own software and/or computer designed for this purpose.

What about for an a380

I'm not sure about this plane. Each version of the A380 has slightly different take off speed. Many links on the internet say around 150 knot, but I can't find any reliable source yet.

The answer can only ever be typical since exactly the same aircraft, wth exactly the same load, can have different speeds on different days or at a different airport or even on different runways at the same airport.

I should add that assuming the same weight, the biggest factors are the pressure altitude, temperature and required obstacle clearance although the latter is not a consideration at most commercial airports.

For the A380, related video on Youtube: Airbus A380 Take-off Time.

authors: Мелентий Акинфеев


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How do ER models store more fuel?
The whole purpose of an ER model is to increase range and by doing that you need to increase the amount of fuel stored in the wings. EX: Boeing 737-900, Boeing 737-900ER. Is the wing area increased or is their another way to increase fuel capacity.Source:(https://en.wikipedia.org/wiki/Boeing_737_Next_Generation#/media/File:Lionair_737-900_ER_first_flight.jpg)

Weird persepctive in that photo: the right wing and stabilizer look half-size.

My understanding is that in most airplanes, fuel capacity is not limited by volume but by weight.  The non-ER model already has plenty of space to store as much fuel as the ER model, or more; but that would make it too heavy to fly.  The ER model might be designed with stronger structures, more powerful engines, etc, that allow it to not only hold the fuel but also lift it.

@NateEldredge, in most aircraft loading cargo to MZFW plus full tanks will get you over MTOW, but full tanks alone won't by far. So the ER models do have use for larger tanks.

@JanHudec Yeah, if full fuel tanks alone would get you over MTOW, then the fuel tanks are probably just too big. - haha

If load full tank alone with little cargo you maybe an aerial tanker and not commercial flight.

@DavidRicherby - that's a demonstrator plane - it's got the standard wing on the right side, and the larger, ER wing on the left side.  ;)

Not all fuel is stored in the wings. Some is also stored in the fuselage. The ER variants have a larger, or additional, centre (fuselage) tanks at the expense of cargo bays volume.
The centre tank is located between the wings to minimize the change in centre of gravity as the fuel is consumed. The wing spar, which must go through to provide sufficient structural strength, does not allow the cargo bay to be continuous in most designs anyway.
The ER models may be also fitted with more powerful engines to increase the maximum take-off weight (engine out performance is usually the limiting factor), so the plane can still take reasonable amount of payload when the tanks are full.

Indeed engine performance is definitely an issue in the particular case of the 737-900ER. They already had to extend the landing gear in order to fit larger engines under the wing for it and it still has an insanely long takeoff roll (9,843 ft ! )

@reirab that surely isn't the takeoff roll but the the take-off run required / accelerate stop distance required

@reirab, it would seem to me that the long take-off run is more due to the rather high take-off speed, which would be due to the relatively small wings that were originally designed for much smaller aircraft. The take-off distance required grows with square of take-off speed.


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Do windows on the side of the fuselage increase drag?
I wonder this because I'm not too sure glass is easier for air to travel over than metal.

The simple answer is yes, but it is not the material that makes the difference in drag production.  The difference between painted aluminum or composite surfaces and glass is negligible.
Where there are windows, there are likely to be seams, transitions and other variations in the skin of the aircraft.  These variations can cause turbulence in the air flowing over the skin which can induce drag.
This is why gliders have such smooth surfaces and contours.  The airflow remains attached to the surface in laminar flow which minimizes drag.  Even bugs stuck to the leading edge of the wing can degrade performance.

It's worth noting that with modern composites the exterior pane of the windows could theoretically be bonded into the structure, all but eliminating the seams and variations described above. Doing so would however be a major sacrifice in the ease of maintenance, which is why it's typically not done.

With the size and speed of airliners, laminar flow is restricted to the first few percent of its surfaces. All passenger windows are well within the turbulent boundary layer, and their aerodynamic drag is negligible.

The long length of an airliner fuselage ensures turbulent flow at the station of the cabin windows, so their only contribution to friction drag are the gaps between metal and polycarbonate. The transition from a laminar to a turbulent boundary layer happens before the windows start. In Sighard Hoerner's classic Fluid Dynamic Drag we find in Chapter V these figures on the drag of surface imperfections:

The size of the gaps and the dynamic pressure at their location drives their drag contribution. Let's assume the windows are 0.4 m high, the grooves 2.5 mm (0.1") wide and shallow enough to have a drag coefficient of 0.008. Let's further assume we talk of a Boeing 747-200 with 100 such windows per side and restrict the drag calculation to the crossflow over the vertical part of the gaps. The full opening area of all gaps is $2\cdot100\cdot2\cdot0.4\cdot0.0025$ = 0.4 m² or 0.078% of the reference area of the 747. Wikipedia gives the parasitic drag coefficient of the Boeing 747 as 0.022, so the windows contribute one threethousandfivehundreth of that drag. Negligible, in other words.
But there is another source of drag: The windows are heavier than the metal which they replace, and to carry them around will increase induced drag. If we again assume 200 windows for a Boeing 747-200 at 7 kg each (these are from pre-polycarbonate times!), they weigh a total of 1.4 tons. This is 0.8% of its empty mass and equivalent to 12-14 passengers. To find the impact of this mass on a long-range flight over 6000 NM, we can use the Breguet equation; once with and once without the 1.4 tons of additional mass. The empty mass of the Boeing 747-200 plus 50 tons of payload is 228,100 kg, its L/D is 16, the specific fuel burn of its JT-9D-7 engines is $b_f$ = 0.0000184 kg/Ns and the cruise speed is Mach 0.84, which equates to $v$ = 250 m/s in FL 350:
$$m_1 = m_2\cdot e^{\frac{R\cdot g\cdot b_f}{v\cdot L/D}}$$
When we use $R$ = 11,112 km and run this once with landing masses $m_2$ = 228,100 kg and again with $m_2$ = 226,700 kg, the difference in $m_1$ is bigger by a factor of 1.65 (the take-off masses $m_1$ are 376,584 kg with and 374,237 kg without windows), so carrying the windows around costs the Boeing 747-200 911 kg of fuel or 0.61% of the total fuel mass per flight. This is one onehundredsixtythird of the total drag - still not much, but fourty times as much as the absolute contribution of the windows to friction drag (if we assume that the 747 flies at the polar point for optimum range).
This explains why conversions of airliners to freighters almost always replace the windows by metal plates but don't care that much about the gaps they leave. In the case of the 747 pictured below they are certainly big enough to be visible from afar.

A Japan Airlines Boeing 747 passenger-to-freighter conversion featuring aluminum window plugs. (Photo credit: Flickr)

Nice answer including the relative influences

It might be better to say NM for nautical miles instead of the symbol for nanometers.

@Ruslan: Good idea, have updated the answer.


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What are some advantages and disadvantages of have the wing on top of the airplane?
Most commercial airplanes have the wings on the bottom of the aircraft to lift the body better, but what about the sugar volt concept that has the wing on the top

see also here and here and here

In smaller aircraft, a high wing is less likely to naturally enter a spiral dive; the low CG (center of gravity) relative to the CL (center of lift) means the plane tends to return to a wings-level attitude instead of staying in a bank if a thermal kicks a wing up. This isn't as much a concern with something as big as your pictured airliner concept.
Larger high-wings mean there isn't a big wing spar and fuel systems running across or just underneath your cargo deck. This is a major reason military transports are high-wing, so the deck can be flat without taking up usable cargo volume raising the entire deck above the wing spar (the high wing also keeps the engines safe from the hazards of "unimproved" landing strips in forward bases). However, in a commercial airliner, it means that spar is now running through your passenger cabin, which is why you don't see it much on jet airliners (the Dash 8 and other turboprops use it by necessity, and typically require a "camel hump" to get the spar up out of the cabin). This concept seems to split the difference, using a thin brace underneath the fuselage to reinforce a thinner high-wing spar.
High wings, especially swept wings on high-mass planes, have an increased tendency to Dutch roll. This is a "stable instability" where one wing gains lift due to a slight crosswind or yaw/sideslip, lifting that wing and inducing a bank, which creates a sideslip toward the other side which lifts that wing and induces a sideslip in the other direction. This ultimately results in a circular or figure-8 rocking motion of the fuselage not unlike the rolling of a ship, which can make passengers queasy.
High-wing aircraft tend to be more susceptible to this because their center of gravity is below their center of lift, and so their natural tendency is to return to wings-level, but on large heavy aircraft this settling takes time, during which the plane develops the sideslip that lifts the opposing wing, causing the overcorrection that continues the rolling motion. To counteract this, large high-wing aircraft are usually designed with some anhedral (downward) angle in the wing. This first lowers the center of lift, as some of the wing is now closer to the center of mass. More importantly, the lift vector of each wing now points outward from the fuselage instead of directly up in opposition to gravity. These two changes combine to relax the plane's natural tendency to self-level, and thus the tendency to Dutch roll, at the cost of keeping the pilot a little busier making small inputs to keep the plane level.
Low-wing aircraft tend to avoid Dutch roll in the opposite way; their center of gravity is above the wings' center of lift. Because of this, the plane will tend to remain in a banked angle, similar to a high-wing with anhedral but for different reasons. Because this can lead to instabilities like spiral departures including the dreaded spiral dive, low aircraft wings are typically given a dihedral (upward) angle, which gives the aircraft some self-stabilizing characteristics at low bank angles while still avoiding Dutch roll.
Lastly, as illustrated by aeroalias's answer, high wings have high engine mounts. Most modern airliner designs have under-wing engines which can be accessed from very near the ground (either standing or on a simple stepladder), and removed from the aircraft while supported with fairly simple cradles on casters. Engines mounted high on the airframe (such as on high-wing aircraft but also the fuselage-mounted engines of T-tails and the centerline engine of tri-engines like the DC-10 and 727) can require a cherrypicker to get to, and powerful accordion lifts to support the engine as it's being removed. This increases maintenance costs and reduces the opportunity for meaningful inspections at the gate.

So your saying that the lower the brace the less risk of dutch roll

Not exactly. Dutch roll is most likely to occur when the center of gravity is below the center of lift, but not too far below. In this configuration, the aircraft's weight causes it to want to settle back to a level attitude from a minor disturbance, but the proximity of the CG to the CL, unlike with an extreme weight-lift separation like a parachute, means this settling is slowed especially on massive aircraft, so the bank has sufficient time to induce a sideslip, causing a natural overcorrection as the plane settles, perpetuating the rolling motion.

because of its size it can avoid a dutch roll. Sorry for all the questions I am having a little trouble understanding the information

It's OK. I was saying that the concept aircraft in your picture, though it's a high-wing design, might avoid this tendency to Dutch roll if the braces from the bottom of the fuselage up to the wing produce aerodynamic lift. If so, two things will happen; the center of lift will be lowered, as the lower wing is producing some of the total lift, and also the brace, being at such an extreme angle from level with the ground, will introduce some dihedral into the overall lift vector of each side of the wing, which has stabilizing qualities.

What I have noticed about the Sugar Volts wings in that they have a dihedral angle and a anhedral  angle

Between the join of the brace and wing, you're right, there's a slight anhedral in the main wing. That looks like it's designed more as a counter to the very thin wing, which will flex upward to create a dihedral angle in flight, further raising center of lift and exacerbating rocking behaviors. The brace further helps to limit wing flex, and also has the potential for generating lift lower on the fuselage and at a very high dihedral angle which will stabilize the aircraft.

Raymer gives quite a few thoughts on this as well in his book "Aircraft Design - A Conceptual Approach"

Isn't wing flex like a dihedral angel. Meaning the 787 has wing flex, but would that be considered a diherdral angle.

And can you also explain to me what a spar is and how it affects the cabin thanks

The SUGAR Volt and SUGAR Freeze concepts use a high wing purely to make effective bracing possible. It is a design for a world where oil costs $200 per barrel and above. Mainly, two things make its aerodynamics much more efficient than current designs:

A very high aspect ratio of its wing, enabled by the bracing, and
A lower flight Mach number, which in turn makes the wing more efficient by requiring less sweep. Boeing doesn't give a Mach number in their web page, but I would bet it is somewhere around 0.75. See here for a discussion of a very similar design.

Todays airliners use a low wing to enable them to stow away their long landing gears and to put the wing spar below the passenger deck. Long gears make it possible to stretch the fuselage and still be able to rotate during take-off. Large high-wing aircraft, with their low fuselage position, are easier to load and unload, at the price that the fuselage taper has to start shortly aft of the landing gear, so no stretching is possible.
Both concepts use rather speculative engine designs, in case of the SUGAR Volt even one with hybrid natural gas / electric propulsion with onboard batteries. The SUGAR Freeze uses a less speculative engine burning liquefied natural gas. In the SUGAR study, Boeing set the goal to reduce fuel consumption by 70%.

The position of the wing is determined by the required stability, the necessity to land in unprepared runways, etc.
In general, the high wing aircraft have more lateral stability compared to the low wing design. In case of low wing design, the desired stability is achieved by dihedral.
The low wing has the advantage of easy maintenance as they are near to the ground. In case of high wing, it usually requires specialized equipment for servicing the engine etc.

source: www.aviation-news.co.uk

Source: www.robins.af.mil
Another advantage of high wing is that the aircrafts can be landed on unprepared and semi-prepared runways as the high wing (and engine position) offers some protection against debris.

Source:www.saairforce.co.za
Also, in case of high wing aircraft, the ground effect is lower. This prevents the smaller aircrafts from 'floating' and improves the landing characteristics.
Form structural point of view, the high wing aircrafts can have a flat floor for easy loading/unloading and using standard pallets. In case of low wing, the spar will run through that section of the fuselage. On the other hand, a high wing design limits the cabin height for the same reason.
In case of civil aircraft, the ease of maintenance is one the main reasons for using low wing.

Good answer it makes sense that it is easier to manage the airport needs to get airliners in and out of the airport quickly and with a high wing it would take a long time to manage.


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What is this feature on a Piaggio P.180?

(wikimedia.org)
What is this feature on a Piaggio P.180?
I believe it's called a dolphin tail, but why is it exactly there and what is it for and why don't all airplanes have this?

It's called a strake, this question explains what they're for and how they work

My question is different because I have a few other questions that I want answered instead of just one question.

I don't want to be difficult, but I don't see anything in this question that isn't answered in the other one: it tells you what strakes are, why they're positioned at the tail, and which types of planes often need them. If you're sure that your question is different, I suggest that you edit to give some more information about exactly what isn't answered in the other one.

why can't all airplanes have this - who said that they can't?  Whether they are required or not or would improve performance is another matter.

The airfoils shown are delta fins.  They provide lateral stability during higher speed flight.  It helps to reduce dutch rolling tendencies and to prevent deep stall characteristics.
So much so that on the Learjets I fly, there is no need for an operable yaw damper.  There is also no stick pusher or stick puller system.  Older Learjets without delta fins are required to have those two systems installed.
https://en.m.wikipedia.org/wiki/Piaggio_P.180_Avanti


text:
Is the landing gear controlled by the pilot or is it automatic?
I have been watching a few aircraft landing videos in crosswind situations and I noticed that if the airliner missed the runway the landing gear would go back into the aircraft. So I'm wondering if this system is automatic after a takeoff or if it's controlled by the pilot manually?

@mins When would the landing gear go up automatically?

The landing gear system is operated by the pilots. The extension and retraction, depend on the action from the pilot monitoring, on 2 pilots operation.
The pilot has a lever on their panel, on which they select the extension (down) and/or retraction (up).
Some aircraft has a system to avoid extending them on high speed, to avoid some damage, and on the ground, avoiding retracting, for obvious reasons.
There are lights, green and red, indicating their position.

To make this really good, you might want to edit in the need for positive rate of climb and link this to the flap retraction schedule.

Fun safety design fact: notice how in this diagram the end of the lever for the flaps looks and feels like a little wheel, reminding the pilot that they are manipulating the landing gear and not some other control.

@EricLippert the end of the lever for the flaps euhm, did you mean the end of the lever for the gear?

@EricLippert True! And that's why (in a Cessna at least) the lever for the flaps looks like a flap.

Hah I totally misedited that to say the opposite of what I intended. Brains are weird.

It's manual. Once there is positive climb the pilot will retract the gear and flaps to minimize drag.

All landing gear that I know of are all controlled by the pilots. I have never heard of an "automatic landing gear" as you describe it.
As some comments below say, there is one airplane that has/had an automatic gear (Piper Arrow) but it was not really the brightest idea because it could cause in-flight problems if not handled properly.

Early Piper Arrows (and a few other models) had an automatic gear extension feature.  It turned out to be more trouble than it was worth and has been disabled on most aircraft.  I haven't found an authorative link describing it, but google 'piper automatic gear extension' and you'll see what I mean

@DanPichelman Never knew that, another thing to add to my aerospace knowledge!

On the Arrow it was based on airspeed and throttle (I think that it was essentially ram air in the prop slip-stream).  You had to engage the override while practicing stalls or slow-flight or it would suddenly drop the gear on you.

@Adam that sounds dangerous in an unintentional stall - extra drag right when you really want some airspeed! Although I suppose it could help with the pitch down angle

@Adam You also had to engage the override as part of the engine failure checklist.  Otherwise, the auto gear extension could ruin a perfectly good dead stick landing.

You also had to be aware of it for a short field takeoff over an obstacle.  The gear could not be raised until you had enough airspeed unless you override the auto-gear.

As the other answers point out, it generally is operated by the pilots.
In the last project I have participated in, though, flap and gear control was performed by an automated system (see slide 17). The control system was automatically deploying the flaps and gear at a specified location during the final approach, without any pilot intervention.
In the future there might be more aircraft that will use such automation, but not before the appropriate amendments will be done to the regulations and not before one such system will be succesfully certified.

As soon as there is a positive rate of climb, the gear is retracted because it is a large contributor to drag on the aircraft, effectively reducing its climb performance.
As a passenger you can feel this on some aircraft when the gear is deployed as you can feel the drag on the aircraft (and depending on where you are sitting, you may be able to hear the gear deploying).
Due to its large effect on the performance of the aircraft, in some aircraft the gear is also used as an impromptu air brake to reduce the speed of the aircraft - although in most modern aircraft, this function is taken care of by the air brake/spoilers.
Gear is retracted manually, usually by the pilot observing, and not by the pilot flying (PF). Usually the pilot observing will say "positive rate, gear up" and then move the lever to retract the gear - this is what you are observing in those videos.

"As soon as there is a positive rate of climb, the gear is retracted " Not always the case, some pilots leave the gear down until there is no more runway left.


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How loud is a private corporate jet?
It's a movie/TV trope that people can talk to each other and even whisper on commercial airliners in flight.  In a story, it’s pracical to confront the reality of the experience and have characters have to deal with the noise when flying.  But, how does a private jet compare?  Will an intern flying with the big boss for the first time find it refreshingly better, or even worse, or what?

I suggest that this can't really be answered without specifying the particular jet.

It's certainly reasonable to think a business jet cabin is quiet. Several business jet makers pride themselves on having models with quiet cabins. It varies a lot depending on the business jet, and exact numbers for the cabin sound level aren't usually listed.  It varies for airliners too with the A380 being an example of a very quiet jet and the 777 being noticeably louder.
If you're on a luxurious G280 or G650, the sound level would be relatively very quiet at less than 50 db (unofficially).  Even other private jets from my limited knowledge allow you to have conversations at even a few feet of distance without much struggle.  If you were operating an old loud engine like a Learjet 24 (which actually had turbojet engines) or a GII, the sound would probably somewhat limit conversation.
Exact sound levels are hard to find, in part because measuring a consistent sound level depends on so many factors, including cabin configuration, airspeed, engine thrust, air conditioning status, and position inside the aircraft.  Engine loudness, which is only part of the picture, is well studied and published (example).
Loud jet engines are rarer these days thanks to variety of factors, including the fact that operating loud jets is just plain illegal nowadays in many countries.  They actually make hush kits for older engines to get them down to legal levels.


text:
Why Helicopter compulsory need helipad to land?
Our Country ministers helicopter didn't land because there is no helipad exist in my location, helicopter needs small place to land, then why Helicopter compulsory need helipad to land?

Anyone even attempting to answer rather than speculate would need a lot more information than that. Most likely it's a combination of insurance (safety...) rules, local regulations, national law, and ATC procedures in the area. But without knowing about all those it's impossible to know.

Maybe they needed to refuel? Just speculation - not enough information in the question to really answer this one.

Helicopters don't need a helipad to land. It is simply safer landing in a helipad. I think the decision was taken in view of safety not to land because of the presence of the minister on board.
See this picture.

That said, why did they come in helicopter if there was no helipad?


text:
Why does An-225 (Mriya) perform a low-pass on its landings?
Today was a big event for aviation fans where I live (Warsaw, Poland, EPWA). We have had a visit of Antonov 225 (Mriya).
Today, but also as I saw in other videos, it often (always?) performs a low-pass first and only then lands. Why is that? I bet this is about safety, but...

is it mandated by some official rules?
or by some internal rules of the operating airline?

What kind of information does the pilot need which they wouldn't get by reading the maps, diagrams or by talking to ATC?

This wasn't an airshow, just a cargo trip?

@GdD Yeah, a cargo trip (with medical supplies! I wonder what led to the An-225 being roped in for that!) from China.

Just an educated guess, it's probably to have the tower check that the landing gear is down and locked,

Trivial, perhaps, but the crew know that the aircraft attracts attention wherever it goes. Maybe they're just showing it off a bit. Good public relations for Antonov.

As of the time of writing this answer, this only appears to have happened in one out of the last 6 flights of the AN-225 (the same flight into Warsaw you mentioned, https://www.flightradar24.com/data/aircraft/ur-82060#245b19c0) so I can't say that this is an official "rule", a standard of any kind or any procedure regarding the AN-225.
There are 2 other videos of that particular landing on YouTube:

It is clear in both videos that the first approach is done with the landing gears up, most likely on purpose "for the show", of course with coordination with ATC.
If someone is fluent in Ukrainian they can confirm it quite easily since the communication between the pilots can be clearly heard in the video you provided.

The best answer?  Most likely, they are getting in practice approaches and pattern work while saving their tire life (gets pricey having to replace 36 tires for some touch and go practice).

There are many possibilities. It might have been a landing gear check, or maybe the crew noticed something wrong last minute and performed a go-around at last second. There aren't much regulations on low-passes, but usually pilots do low passes because they either have not been in that airport and are not experienced, or they are flying an uneasy plane, for example, the AN-225. They do this because they want to get a feel for the approach, that way, it's harder to make a mistake, and you'll feel more comfortable on landing.

Everything beyond the 1st 2 sentences makes little sense for experienced pilots flying into an international airport.


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Cross Country Planning: What do I put in the NavLog for the GPS route?
I'm a student pilot. My homework this week is to plan a cross country flight from point A->B using dead reckoning and on the way back B->A using GPS and flight following.
So the question is, do I put on my NavLog the dead reckoning (course heading, estimate time established, estimated fuel burn, etc... for each leg) only for the A->B route? What do I put in for B->A (GPS flight). I assume: basic estimation of fuel burn for the whole flight, straight line distance; how about take off and top of climb, things like that...? How do you usually do this?

I can't tell you what specifically to include on your navlog (that's a judgement call you make as a pilot - you determine what has to go on the paper to satisfy yourself that you can complete the flight), but I can give you a crash course in my theory of navigation, and a practical example of how I decide what to put on my navlogs.

What's the point of the Navlog?
At its core a navlog is a list of waypoints such that you could find your way from Point A to Point B via the listed route by using some navigational system.
Ideally the navlog should be usable with at least two independent navigational systems in case one breaks, and for a VFR flight one of those navigational systems should always be "Looking Out The Darn Window!" (the window rarely breaks).
For purposes of this discussion I'm going to focus on waypoint selection and a few other housekeeping tasks. I'm ignoring stuff like calculating headings because while that stuff is important it's also just mechanical math: The waypoint selection requires you to exercise some judgment as a pilot.

A Practical Example: KGON to KMGJ and back.
This is a nice 100 mile flight to use as an example. Let's plot the outbound trip using pilotage and dead reckoning, and the return trip using the GPS. (This is going to get photo-heavy, so I'm burying them in links.)
The first thing you do is draw the straight line between the two airports on the chart. Then follow the line from Point A to Point B and mark off convenient landmarks. I chose Chester Airport, the New Haven railroad/highway/river, abeam the Waterbury-Oxford Airport, the lake & prison north of Danbury (also abeam the Danbury airport), and the Hudson River (you can't miss it!).

Pilotage Tip: Airports (at least the larger ones) make great landmarks. They're also convenient landing places if you have a problem, so including them as waypoints is a double win.

Almost all of these legs can be completed by pilotage (you can always see the next waypoint/landmark), but one of the legs (Danbury to the Hudson) is about 24 nautical miles and on a hazy summer day you might not be able to see that far. You should therefore be prepared to fly at least this leg by dead reckoning (point the nose in the right general direction based on the heading you calculated, and fly until you see a big river).
The navlog that Skyvector generates for this is somewhat unfriendly-looking, with lots of latitude/longitude fixes in it, and automatically generated ones from Foreflight and similar tools will look about the same. When you write up your navlog you can give each waypoint a descriptive name like I did above so you can remember what you're looking for in case your sectional blows out the window mid-flight.

So that takes care of the outbound trip with visual waypoints - what about the return trip using the GPS?
GPS systems have convenient databases of airports, intersections, and navaids, so we draw the same straight line, then look at the chart and find the waypoints between our two airports that the GPS will know about. The result looks like this and produces a navlog with nice waypoint names.

GPS Tip: I avoided using Lat/Long fixes in the GPS plan in favor of fixes that you can type in on any GPS, so this is fast and easy to enter on a Garmin 430/530 for example. Newer GPS systems like the touchscreen Garmins let you do "rubber-band flight planning" where you can drag your route of flight around and easily create waypoints wherever you want - you could even set up the same track I did for the outbound flight if you want.

Since you're flying under Visual Flight Rules you're going to want to note down Visual references to go with this navlog (because again if your instructor is anything like mine was your GPS is going to suddenly fail on the return trip while you're merrily following the magenta line).
For this return trip the visual references would be Stewart Airport (and the Hudson River beyond it, even though it doesn't have a dot on this plan), the city of Brewster (which doesn't have a dot, but is identifiable as a city that has power lines, railroad tracks, and a highway immediately east of it), the Danbury airport (KDXR), abeam the Bridgeport airport (at TRUDE), and from there on you can cheat and use the shoreline (even if the entire electrical system died you can still find your way back to Groton by following the shore until you recognize "home").

What about that other stuff? (Airspace, ToC/ToD, ETE, fuel burn, etc.)
There are a few important things you don't get by picking out the waypoints the way I did it above.  The most obvious one is Airspace -- you'll notice the course I've plotted cuts right through the Stewart (KSWF) Class D airspace, and Orange County is really close to the Class D ring. Unless you're in a helicopter there is no way you could fly above the Stewart airspace and then descend into Orange County along the plotted route without exceeding VNE, so you're going to have to plan on talking to Stewart's tower and requesting a transition. Note the tower and ATIS frequencies and pick a spot along your course to call the tower up to request the transition. (Same goes for the return trip - we plan to cut through right over the airport so we need to call them and ask.)
Similarly you want to note the tower frequency of any airport you're passing so you can monitor it, and so you can call them up if something goes wrong. This information is on the chart, but printing it in big letters on your navlog makes it easier to find.
Something else most flight instructors want to see you including are Top of Climb and Top of Descent (along with a calculation of fuel used in the climb or descent) - you get this the day of the flight by determining what altitude you want to climb to (based on the wind data you got in your pre-flight briefing) and referencing the aircraft's performance charts. You'll add a little mark to the course line on your chart for TOC and TOD, and I usually put it in a "notes" area on my navlog (TOC xx minutes elapsed and if there's a convenient visual reference I note what it is).

General Tip: I try to include some waypoint that will be at or near top-of-climb/top-of-descent on my flight plans - if you have a reasonable idea of how your plane performs you can usually pick something within a few miles for most reasonable wind conditions. Doing that makes it easier because I can use the time-fuel-distance charts in the POH to fill in the estimated time enroute to that waypoint (or waypoints if it's a long climb) and the fuel burn: One less thing to calculate.
  I did not go out of my way to do this on the charts above.

You should also be calculating an estimated time enroute between each waypoint based on your calculated groundspeed (again you'll work this out before you depart based on forecast winds - you'll see that Skyvector computed it for us based on a 100-knot airspeed and the wind data available as I was typing this).
This seems a litle crazy for 10 to 30 mile legs like this (about 6 to 20 minutes enroute between each waypoint, but if we go back to the idea of using this navlog over a wide-open desert we may have an hour or more between waypoints, and cross-checking estimated time versus actual time lets you know if the winds are significantly different from the forecast values.
The estimated time enroute in turn gives you your fuel burn for each leg: You know your engine burns a certain number of gallons per hour, and you know how many hours (or fractions of an hour) each leg will take - multiply to get your fuel burn.

Don't Run Out Of Gas Tip: Plan conservatively: Round fuel consumption numbers up to the next half-gallon or gallon.

Finally every navlog has at least one other key element: The heading you should be flying: True Course ± Magnetic Variation ± Wind Correction Angle ± Compass Deviation = Magnetic Heading - What you steer on the compass. Skyvector calculated this for us (with the exception of the Compass Deviation which it can't know) but if you're doing the flight plan manually you need to do this math yourself.
Again you would do this right before your flight, with the most current wind data.

In the end of the day what you put on your flight log is your choice (although your particular instructor may require some things). You may want to elaborate a bit on your GPS course. Are you mapping point to point on the way back (flying directly from B->A or are you using GPS along with nav aids on the ground. For that matter what kind of GPS are you using, A handheld> An in cockpit like a Garmin 430? iPad with Foreflight or the such?.
I am a big user of Foreflight and really like the moving maps it has but when flying VFR you should always have multiple ways of navigating ready should a give method cut out (like an iPad crash midflight etc). Lets say you are using the GPS to fly direct from B->A in that case you still know the distance and can calculate your fuel burn (climb out included). Since its point to point you are in theory flying a single heading the whole time. As such your log should have that single heading on it and you should be using your GPS to make sure you are maintaining your course. Keep in mind GPS will read out your ground track not the heading of the aircraft. In other words if you have a cross wind your compass/heading indicator will not be the same as your GPS track.

When my planned route is GPS-direct (no intermediate waypoints), my route of flight looks something like "KXYZ Direct KABC". In that case, I create two quasi-waypoints on my NavLog: TOC (top-of-climb) and DP (descent point).
I calculate time, distance, and fuel burn for the climb based on appropriate table(s) in the POH (adjusted for winds as necessary), and enter those for the TOC waypoint (marking the calculated point on my chart).
I calculate my descent profile based on my planned descent airspeed, rate-of-descent, cruise altitude, and predicted winds; I want to be stabilized at pattern altitude (or appropriate overflight altitude) before I reach the airport. I enter the DP based on those calculations (and mark the calculated point on my chart).
Then it's a simple matter of subtracting the Climb and Descent legs from the total distance to derive the Cruise leg distance with appropriate time and fuel-burn based on the POH (adjusted for predicted winds, of course).
The resulting NavLog has four waypoints: Departure Airport, TOC, DP, and Destination Airport.


text:
Which aircraft manufacturers still include Vertical Situation Displays (VSD) feature in their cockpits?
I'm curious about the aircraft manufacturer names who still interested in including the VSD on lower part of Nav Display (I read about Boeing 737 only). Are there any other guys on this filed still? I know this would be useful during the landing and takeoff.

Do you mean airlines?  The aircraft can be configured to show this or not.

Aircraft manufacturers like Boeing, Airbus etc.. Is this technology outdated?

What do you mean by vertical situation display? I only know vertical speed indicator and horizontal situation display.

VSD
Boeing have a patent on a VSD (Vertical Situation Display), which is part of the Honeywell EGPWS (Enhanced Ground Proximity Warning System) which first appeared as an option on 737s about twelve years ago I think.

The system will be offered by early 2003 as a customer option on in-production 737s and by retrofit on 737-600/-700/-800/-900 airplanes already in service. Implementation of the system on other Boeing models is under consideration.

- Boeing "Aero" magazine

I don't know if Boeing offer licences at acceptable terms to their competitors, or if Honeywell make available, to other aircraft makers, products that incorporate features licensed from those patents.
CFIT
It is possible that other manufacturers have equivalent options for alerting pilots of potential CFIT (Controlled Flight Into Terrain).
TAWS & EGPWS
The FAA, for example, requires aircraft be fitted with systems that comply with TAWS (Terrain Awareness Warning Systems) requirements. EGPWS systems satisfy that requirement.
TAWS requires a terrain awareness display but I dont think it requires something specifically like Boeing's VSD.
Airbus for example, on at least their A350 and A380 models, have a navigation display that incorporates "vertical flightpath data". I guess they don't call it a VSD. They also have what I think is a fairly common type of terrain display showing "peaks" ahead of the aircraft.

- Sources: FlightGlobal and Airbus
RNP
It may be that some of the issues addressed by the VSD are, for many airports in mountainous terrain, taken care of by RNP (Required Navigation Performance) which prescribes the required navigational accuracy of the aircraft's navigation systems. Generally the aircraft is required to be able to follow an approach path that consists of a sequence of curved three-dimensional paths to the runway that avoids terrain. I imagine this path is pre-programmed into the navigation systems along with the go-around paths.

So VSD would be only on Boeing aircraft, other manufacturers like Airbus do have equivalent Technology, but it is not called as VSD, instead it is CFIT. is that right?

CFIT is "Controlled Flight Into Terrain" (or "Unintentional Landing") and is to be avoided at all times, as it usually costs lives. VSD is Boeing's term for their EGPWS that meets the FAAs TAWS requirements. Airbus have a similar system, but with a different name than VSD, who's job is to help the pilots avoid CFIT. (For definitions of the TLAs, see RedGrittyBrick's excellent answer.)

@FreeMan Also known as "cumulo granitus".

The VSD can SHOW the terrain data from EGPWS, but it is not PART OF the EGPWS.  It's common to have EGPWS without the VSD.  In fact, the more common use of a VSD is to show the vertical path of the aircraft in relation to the flightplan in the FMC and crossing restrictions that are programmed into this plan.  It's an enhancement to the "moving map" display, but it's a mistake to equate it to EGPWS.  They're not the same, and EGPWS has been around much longer.

The Boeing 747-8 and 787 have the same system installed.

There are similar vertical profile displays available on Boeing 787, Airbus A380 and Airbus A350 aircraft.
Here is an image of the 787's flight deck showing the VSD on the copilot's side:

Source: Airliners.net

Good info...do you have sources to include here by chance?

Below is a link to a 787 flight deck picture on airliners.net. The VSD is shown at the bottom of the navigation display presented on the right inboard screen. A380 (possibly A350) can be found on that site, too. Another useful resource is smartcockpit.com, but I haven't looked at it in years. Link: http://www.airliners.net/photo/Boeing/Boeing-787-8-Dreamliner/2112928/L/&sid=d43bc3372c1fc5a10481e6281fba2d06

For the smaller aircraft market (and the big guys for that matter) many of the common EFB applications will display this information.

(source)